[Dolphinsiu]

I use 3 methyl 3 pentanol and concentrated phosphoric acid to form hexene.

But why we need to use ice bath to collect the distillate?
(I only answer that the the distillste is highly volatile, is it enough?)

[alphahydroxy]

Yes, I think you're right. I imagine you just use the ice bath to ensure that the product will condense ok in the receiver flask.